Various types of rotary drill bits or rock bits may be used to form a borehole in the earth. Examples of such rock bits include roller cone drill bits or rotary cone drill bits used in drilling oil and gas wells. A typical roller cone drill bit includes a bit body with an upper end adapted for connection to a drill string. A plurality of drill bit segments, typically three, is frequently used to form the bit body. Each drill bit segment preferably includes a support arm which extends from a lower end of the bit body. Each support arm also includes a spindle or journal protruding generally radially inward and downward with respect to a projected rotational axis of the bit body. An enlarged generally cylindrical cavity is preferably formed in the bit body to receive drilling fluids from the drill string.
A cutter cone assembly is generally mounted on each spindle and rotatably supported on bearings acting between the spindle and the interior of a cavity or chamber formed within each cutter cone assembly. One or more nozzle housings may be formed on the bit body adjacent to the support arms. A nozzle is typically positioned within each housing to direct drilling fluid passing downwardly from the drill string through the bit body toward the bottom of the borehole being formed. Drilling fluid is generally provided by the drill string to perform several functions including washing away material removed from the bottom of the borehole, cleaning the cutter cone assemblies, and carrying the cuttings radially outward and then upward within an annulus defined between the exterior of the bit body and the wall of the borehole.
Various techniques have previously been used to weld or attach the drill bit segments with each other to form a rotary cone drill bit. U.S. Pat. No. 4,054,772, entitled "Positioning System for Rock Bit Welding" shows apparatus for positioning three drill bit segments relative to each other followed by laser welding to join the drill bit segments with each other to form a bit body with three support arms and respective cutter cone assemblies extending therefrom.
U.S. Pat. No. 3,907,191, entitled "Method of Constructing a Rotary Rock Bit" discloses a method and apparatus for constructing a rotary cone rock bit with an accurate gauge size from multiple drill bit segments. The '191 Patent discloses "scissoring" of drill bit segments relative to each other to establish the desired gauge diameter for the resulting rotary cone drill bit.
U.S. Pat. No. 3,987,859, entitled "Unitized Rotary Rock Bit" discloses a method and apparatus for positioning drill bit segments relative to each other to allow an electron beam gun to form a rotary cone drill bit by welding the segments with each other. The '859 Patent also shows inserting a dowel in adjacent holes in the respective drill bit segments to aid in aligning the drill bit segments with each other prior to welding.
U.S. Pat. No. 4,045,646, entitled "Positioning Fixture for Rock Bit Welding" discloses an apparatus which may be satisfactorily used to position drill bit segments relative to each other and to weld adjacent drill bit segments with each other to form a rotary cone drill bit.
U.S. Pat. No. 4,414,734 entitled "Triad for Rock Bit Assembly" shows a triad which may be positioned in respective holes in three drill bit segments to assist with aligning the drill bit segments with each other prior to welding.